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1.E. histolytica is pathogenic, although it was recently shown that all of genotypes of E. histolytica are not equally capable of causing disease. 2.E. dispar is non-pathogenic. Backgrounds Then, the question is if E. moshkovskii is……? 3

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Entamoeba moshkovskii Development of molecular biological method Development of PCR method  was first identified in 1941 and was thought to be a free- living common protozoan species.  The first human isolate was obtained from a resident of Laredo, Texas, who suffered from diarrhea, weight loss, and epigastric pain in  This isolate was named E. histolytica Laredo and shared biological features with E. moshkovskii.  E. histolytica Laredo is identical with E. moshkovskii. Thus, E. moshkovkii is able to at least parasitize in human. 4

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E. moshkovskii  is morphologically similar to E. histolytica and E. dispar.  is microscopically indistinguishable from them.  is biochemically and genetically different from them.  High incidence of E. moshkovskii has been reported in developing countries by PCR in human fecal samples. However, it remains unclear whether E. moshkovskii is pathogenic or non-pathogenic. 6

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we tested the ability of E. moshkovskii to cause colitis and diarrhea in a murine model system. at first, In order to clarify the pathogenicity of E. moshkovskii, 7

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Then, the association between diarrheal episodes and infection with each Entamoeba spp. was examined in children in Mirpur, Dhaka, Bangladesh. These studies were part of a prospective cohort study on diarrheal diseases in newborns, which prospectively followed for diarrheal illness by every other day home visits. 9

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Field research assistants (FRAs) visited each study house every other day and collected information related to child morbidity, especially for diarrheal illness. FRAs collected non-diarrheal monthly stool specimens as well as diarrheal stool specimens from the home or in the study field clinic. All stool specimens were transported from the field to the clinic, then to ICDDR, B. using a cold box. 11

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 Diarrhea was defined as having three or more unformed or abnormal stools (as per the mother’s perception) in a 24 hour period.  A diarrheal episode was defined as being separated from another episode by at least three diarrhea-free days. A total of 1426 diarrheal episodes were recorded during the first 12 months of life in 385 children. 12

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The frequency of E. moshkovskii in diarrheal stools is comparable to that of E. histolytica in Mirpur children. E. moshkovskii (2.95%)E. histolytica (4.63%) E. dispar (0.35%) 5 The 1426 episodes of diarrhea were observed in 385 children during the first 12 months of life

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16 As there are many microbes that can potentially induce diarrhea, the presence of other diarrheagenic microbes was examined in the 42 diarrheal samples that were associated with E. moshkovskii.  standard bacterial culture  fecal antigen detection  multiplex PCR combined with probe-based detection with Luminex beads

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The diarrheal episodes associated with E. moshkovskii were commonly co-infected. No. of other infection No. of samples Percent of infection (%) The application of these state-of-the-art diagnostic techniques in this cohort has on average identified a minimum of two different enteropathogens in every diarrheal stool sample (Houpt E and Taniuchi M personal communication).

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Conclusions 1.E. moshkovskii caused diarrhea, colitis and weight loss in mice. 2.In children in Bangladesh, the new acquisition of E. moshkovskii infection was associated with diarrhea. 3.These data are consistent with E. moshkovskii causing diarrhea, and indicate that it is important to re-examine its pathogenicity. 20 Shimokawa, C., et al. J. Infect. Dis. 2012; 206: